The polyolefin resins have excellent mechanical, chemical, physical properties, and molding characteristics, and are widely used as unexpensive plastic materials. Above all, for example, polypropylenes, polyethylenes, ethylene-propylene copolymers, ethylene-propylene-nonconjugated diene copolymers are blended with thermoplastic resins such as polyester resins, polyamide resins and polycarbonate resins in an attempt to save the weight of said resins and to improve their mechanical properties such as impact properties. However, as the polyolefin resin has no polarity, it is less compatible with such thermoplastic resins and a simple mixing of the both resins can not provide any uniform dispersion, thus resulting in decrease of the mechanical properties such as rigidity, breaking strength etc, and if molded, products may cause peeling on their surface, whereby no compositions having intended physical propterties are obtainable.
In this connection, for the purpose of improving compatibility between polyolefin resins and thermoplastic resins, Japanese Laid-Open Patent publication No.5-287138 has proposed a process for blending olefin elastomers modified by unsaturated glycidyl compounds with polyester resins, and Japanese Laid-Open Patent publications Nos.1-144445, 2-160812, and 2-160813 have proposed bledning processes for ethylene-propylene-nonconjugated diene copolymers modified by glycidyl methacrylate and polyster resins. It is true that said proposed processes could definitely improve the impact properties of the products, but such modified olefin elastomers were found poor in flowability, and represented excessive reactions against the polyester resins so that there could cause a deterioration in flowability of the resulted resin compositions.
Furthermore, Japanese Laid-Open Patent publication No. 7-149960 has proposed a process of using polyolefin resins modified by compounds having a specific glycidyl group, or the compounds having a specific glycidyl group and vinyl monomers to improve the impact properties of thermoplastic resins such as polyester resins and polyamide resins. Although this process may improve the mechanical properties such as impact properties of the thermoplastic resins without fail, it is necessary to use a great amount of modified polyolefin resins in order to ensure a sufficient improvement effect, but such a use may cause decrease in rigidity or breaking strength.
The present invention is to provide a graft-modified polyolefin resin obtained by graft-polymerizing onto a polyolefin resin, a mixture of a compound having specific glycidyl group with an unsaturated glycidyl ester, and a vinyl monomer, and resin compositions comprising said modified polyolefin resin and a theremoplastic resin, said resin compositions being well blanced in mechanical properties such as impact resistance, elongation, rigidity and molding properties.
The present inventors have made an extensive series of studies in an attempt to solve the above problems, and have found that the above object could be attained by using a graft-modified polyolefin resin obtained by graft-polymerizing onto a polyolefin resin, a mixture of a compound having a specific glycidyl group and an unsaturated glycidyl ester, and a vinyl monomer, having thereby reached the present invention.